Timer



Jan. 18,1927. 1,615,012

S. W. HARTLEY TIMER Filed Jan. '1923 fl'il' 2/ a I v If I IV V E IV TOR 561061122 Wflariiep .4 from/Er Patented Jan. 18, 1927.

UNITE STATES SEWARD W. HARTLEY, OF NEW YORK, N. Y.

TIMER.

Application filed January 25, 1923. Serial No. 614,739.

The invention relates in general to an improved form of commutator contact brush, and the invention specifically relates to an improvement in the revolving contacts used in commutators of the type known as timers, usually employed in connection with multiple cylinders, internal combustion engines and in which a rolling brush makes electric contact with plates or segments arranged in an annular track and connected for effecting the desired sequential operation of the sparking devices used in such engines.

A usual construction of such forms of commutators includes a centrally positioned driving shaft to which is pivotally connected one end of a roller contact carrier, the opposite end of which has journaled thereon a contact brush in the form of a roller, maintained in engagement with the track by means of a spring. In such constructions it is vitally necessary that the roller be free to turn with the least possible resistance to its rotary movement so as not only to insure the wearing down of the roller uniformly while in use, but to eliminate any possibility of sticking action due to a flattening of the periphery of the roller. It is equally vital that positive electric contact be maintained with the roller as well as between the roller and track, so as to maintain the necessary continuity of functional activity of the device under all conditions of service.

Accordingly, one of the primary objects of the invention is to provide a simple form of electrical connection with the roller contact brush and which connection will maintain a continuity of electric contact with the roller and at the same time offer a minimum resistance to the desired freedom of rotary movement of the roller as it moves along in bearing engagement with the track. Broadly I attain this phase of the invention by providing electric contact with one end of the roller and as close to the axis as is physically i'iossible while prm iding a broad contact surface.

Another object of the invention is to provide a simplified construction of contact brush mounting which will tend to maintain this continuity of electric contact between the brush and its driving shaft, irrespective of the speed of revolution ofthe roller; irrespective of the position of the parts relative to the vertical and irrespective of the direction of rotation of the driving shaft.

Still featuring the desire to maintain continuity of electric contact the invention contemplates a construction for maintaining the track clear of oil, of the products of oxidation and of other foreign matter, and in this way insure the maintenance of a bright, clean contact between the freely rotating roller and the contact plates or segments forming part of the track.

I attain this phase of the invention by inclining the brush to the track in such way that thebrush has a side scraping or shearing action transversely of the track as it moves bodily along the length of the track.

Further, the present disclosure features the maximum possible extent of contact surface between the brush and track and accordingly in the case of a roller type of brush there is provided a relatively long line cont-act between the periphery of the roller and the succeeding contact plates in the track.

In the form of the invention herein selected for the illustration the roller is in clined so that its line of contact with the track will be slightly offset angularly from its usual position extending transversely of the track or perpendicular to the line of bodily movement of the roller about the track.

Considering 'tae situations either in which the roller so disposed is held positively from axial movement or in which the roller is restrained resiliently from a freedom of axial movement, the result will. be that the roller will not only turn about its own axis as it rolls along the track, but will react on the track with a slight side slipping motion which will have the effect of cleaning the track.

In the present disclosure which features the cushioning of the roller in its axial movement, the tendency of the roller to move axially is utilized electrically to insure a positive contact between the advanced end of the roller and a contact member which functions to convey current with the least possible electric resistance directly from the roller to the element of the roller mounting carried by the driving shaft. In this way the current path is bridged across the resistance which is frequently developed at the point where the roller arm is pivoted to the driving shaft.

Various other objects and advantages of the invention will be in part obvious from an inspection of the accompanying draw ings and in part will be more fully set forth in the following particular description of one form of mechanism embodying my invention, and the invention also consists in certain new and novel features of construction and combination of parts hereinafter setforth and claimed.

In the drawings Figure 1 a view in side elevation looking at the inside of a cmmnutator provided with a brush constituting a preferred embodiment of the invention;

Figure 2 is a side view of the brush. and its associated parts looking at the same from the side opposite to the side shown in Figure Figure 3 is a plan view of the part shown in Fig. 3 looking at the same in the direction indicated by the numbered arrow 3;

Figure lis a transverse sectional view through the track element shown in Figure l and viewing the brush and its associated parts from the position indicated by the numbered arrow l; and

Figure 5 is a transverse sectional view taken on the line 5-5 of Figure 1 looking? in the direction indicated by the arrows and showing the roller contact in its relation thereto in diagrammatic outlines.

In the following description and in the claims, parts will be identified by specific names for convenience of expression but they are intended to be as generic in their application to similar parts the art will permit.

In the drawings and referring particularly to the showing in Figure 1 there is shown in outline the commutator of the type gener ally known as a timer and which includes a flat cylindrical casing encircling an insulating ring 11 in the form of an annulus, the inner periphery 12 of which forms a roller track. The track is formed in part of metallic contact plates or segments 1 each connected electrically to binding posts ll. A centrally positioning driving or cam shaft- 15 is provided with a roller carrier 16 coacting with a coiled spring 17 for main laining a roller contact in operative rolling engagement ilh the track. Described in detail the carrier includes a sleeve 1.) secured to the shaft 15 to rotate therewith and one side of which sleeve constitutes an outstanding lug 20 which bent back upon itself to form a journal 21 in which. is pivot ally mounted a roller arm 22 for carrying the contact roller 18. it will be understood that the structure thus far described follows conventional design and is referred to simply to show the rulaptahility of the inventive features to a known construction.

A structural detail differing from conventional forms and featuring simplicity of structure is the roller arm which is a stock size rod, cylindrical in cross section, and bent into lJ-shaped form to provide two shafts.

One of these shafts 23 hereinafter referred to as a revolving shaft, is pivotally mounted in the bore of the journal 21. The other shaft- 2% constitutes a roller shaft upon which is journalled the cylindrical roller 18. A stop plate 25 constitutes a tie for connecting the free end of the shafts 23 and 2iand demountably secured in place by cotter pins 26 and 27, passed through the shafts adjacent their free ends. The stop plate is provided adjacent the center of one edge with a laterally extending spring seat 28. The coiled spring 17 extends between the seat and a boss 29 formed on the sleeve 19 and acts to swing the arm about the axis of the shaft 23 and in this way maintains the roller in bearing engagement against the track.

One feature of novelty to which attention is particularly direced is that the of the shaft 2st indi *ated by the line (6Z) (Figure is inclined slightly from the usual parallel relation of such shafts with the axis of rotation of the roller arm as a whole indicated in Figure 3 by the line cd. Considered in another way the axis a7) is inclined slightly from a position normal to the plane of the orbit of revolution of the roller in its bodily movement about the track. Considering the relation of the periphery of the roller to the track in any position of the roller on the track and referring particularly to the disclosure in Figure 5, it will be noted that the line of contact between the periphery of the roller and the track. indicated by the line 0 0 7", will form a small angle with the usual line of contact: which extends transversely of the tracl: and is indica ed in Figure 5 by the line 0 71 As it is a fe ture of this disclosure to minimize any resutance to the rotary movement of the roller about its own axis Z). the angle of displacement from normal, i. the angle a o (or Fe 0 will not he as (X21);- gerated as is shown in the drawiiw but will preferably be confined to two or three degrees of :mgnlarity for a very slight cauliug of the roller ax': has hecn found sufficient wiping or :0 give the ocsired side shearing effect on the track.

The end of the roller cylinder is opposite the stop plate 2-5 is engaged by the broad flat free end 3 l of a spring contact ll. in the form of a leaf sawing. The spring is threaded :uljaccnt opposite ends on the shafts 23 and 24. and has its secured end held between the :uljaccntflat end 32 of the journal 21 and the adjacent crotch portion of the roller arm This spring provide a. direct electric connection betwehn the mile" and the partof the carrier secure-fl to th driving shaft 15. By this const "action it possible to conduct the electric current through a single metallic member of low resistance dir ctly from the bearing sleeve 19 to the roller 18 and in this way avoid the electric resistance which frequently develops by oxidation and dirt accumulation between the shaft 23 and the bore of the bearing 2i. This spring contact is placed on the side of the roller towards which it moves in its tendency to creep laterally along its axis 3) when the shaft is turning in its normal forward direction and in which case the roller is turning cloclnvise as .indi :ated by the arrows in the showing in l igure 1. When the device is ii'istalled as part of an :illiOlllOlIlilt power plant it will. be usual, on i-al'opping the engine, for the shaft to lend to reverse from its normal direction of movement. in this case the roller will. lend to move in the opposite direction or towards the stop plate 25. This stop plate is usually a conductor so contact may be provided between the roller and bearing 19 through the stop plate but this n'iight involve a momentary air gap resistance between the roller and stop plate. Accordingly it is preferred in order to maintain the electric conduction through the spring that the spring be at all times under tension sul'iicient to follow up the roller in all positions of the same.

'While it is suggested in this disclosure that the contact spring bear directly upon the end of the roller and in this way insure positive electric contact, it is also desirable to minimize frictional resistance to the rotary action of the roller. It is accordingly suggested that some approved form of anti-friclion means be interposed between the contact spring and the roller and as an illustration of one such means, which will also maintain elliififric ctmductivity with the least possible resistance, one or more metallic washers 33 are illustrated.

in operation it will be understood that the device functions in general. as is well known with timer devices of similar construction. inferring particularly to the operation of the parts herein featured, it will be understood that a forward movement of the shaft clockwise in I' 1 will cause the contact roller to turn freely about its own axis as it moves about the track and the reaction between the track and inclined roller will cause the roller to move in a direction away from its normal inactive position engaging the stop plate and into positive bearing engagement with the contact spring, in case it is not already in engagement with the spring. This spring may give slightly and thus tend to resist the freedom of rotary movement of the roller, but this is immaterial provided the spring does not offer any material resistance to the rotary movement of the roller. The electric current passing from the shaft to the roller may pass through the stop plate, coiled spring and through the roller arm as is usual in similar constructions, but in this case all or at least the greater amount of current will pass through the contact spring due to its greater conductivity and to the fact that current passing over this path does not have to cross the resistance at the surface of the carrier shafts. This resistance becomes material in those cases where rust forms between the revolving shaft and its bearings, and where wear between the roller shaft and the roller tends to destroy the initially free rolling contaiist between these. meniibers.

liy means of a device of the class described it is possible to maintain a continuity of operative condition and this condition is not effected. by the wearing away of the parts. However, even if replacement of worn part-s becomes necessary, it is simply effected by removing the cotter pins, replacing the roller arm, contact plates or roller, which elements constitute the possible wearing replacement parts and the device is ready for continued operation.

\Vhile I have shown and described, and have pointed out in the annexed claims, certain novel features of my invention, it will be understood that various omissions, substitutions and changes in the form and deta ls of the device illustrated and in its operation may be made by those skilled in the art without departing from the spirit of the invention.

Having thus described my invention, I claim:

1. In a commutator, the combination of an annulus providing a contact track, a shaft centrally positioned in said track, an electric conducting member fixed to the shaft to turn therewith, a roller arm including two shafts slightly inclined relative to each other and with one shaft journalled in said member, a contact roller journalled on the other shaft and in rolling engagement with the track, a stop plate extending between the shafts at one end of the roller limiting the axial movement of the roller in one direction, a flat leaf contact spring extending between the shafts at the opposite end of the roller and bearing on the adjacent end of the roller to maintain electric contact with the roller and to provide an electric conductor between said conducting member and roller independently of any conducting function of the stop plate.

2. In a commutator, the combination of an annular track, a member mounted for rotary movement within said track, a cylindrical contact roller carried by said member and maintained with its periphery in bearing engagement with said track,-u1eans coacting with the track for causing the roller to shift axially in one direction as it is rolled along the track and a stop for limiting the axial movement of the roller in one direction and coi'istituting a contact disposed in the path of said axial movement or the roller and in bearing engagement therewith to maintain fill electric contact bet\\"een the shiftable roller and the stop.

3. In a commutator, the combination of atrack, including a contact element, a roller contact positioned within the outlines of and operatively engaging said track, track and roller operatively disposed and coacting to cause the roller to manifest a tendency to move axially across the track as it is rolled longitudinally along the track and a contact spring constituting a resilient stop for limiting the axial movement of the roller Contact.

a. In a device of the class described, a roller shaft, a roller free both to turn on said shaft and to slide axially along said shaft, a spring Contact limiting the axial movementof said roller in one direction and anti-friction means formed of electrical conducting material positioned between the roller and contact.

Signed at New York city in the county of New York and State of New York this 21st day of October, A. D. 1922.

SEVARD V. HARTLEY. 

